How to convert an HTML tree to PDF?

If I understand your question correctly, you wish to convert HTML pages on your site to a single PDF file.

I guess the total HTML files are around 20. So rather than use a tool, you can manually open the pages in Chrome, choose the Print option & "Save as PDF". If you want to merge them into a single PDF, you can use one of the many free online or desktop PDF merging tools.

Using wget (use -r for download recursive) and htmldoc for convert html tree to pdf.

apt-get install htmldoc